Fuel pump with improved oil seal assembly



March 29,1966 JQGQLD' 42, 8

FUEL PUMP win: IMPROVED OIL SEAL AssEMgm' Filed March so, 1964- I ATTORNEY United States Patent This invention relates to fuel pumps of the automobile type and sealassemblies for use therein. l A very satisfactory fuel pump is disclosed in the United States Patent No. 3,135,218, granted June 2, 1964 in the name of Dimit-ar Toschkoit and entitled Pump With Lost Motion Structure About Diaphragm Plunger. In that pump a sealing diaphragm is used to prevent gasoline leakage into the crankcase in the event of pumping diaphragm failure and also to prevent crankcase oil from escaping through a breather hole venting the pumping spring chamber. Occasionally failures have occurred in that and in other types of fuel pumps and a thorough investigation has revealed that the sealing diaphragms,"under certain conditions, could be exposed to violent reversals in curvature during reciprocation of .the diaphragm or piston actuatingplungers extending through the sealing diaphragm. In order to prevent these reversals the pump with its improved sealing assembly herein disclosed was devised. I

An object of the present invention is to provide an improved seal diaphragm assembly for a reciprocating pump, which assembly is not subject to failure due to changes in fluid pressures to which it may be subjected. Another object is to provide a pump in which such an improved diaphragm seal assembly is employed.

A feature of the present invention is an assembly having a plunger and the central portion of a flexible sealing diaphragm movable as a unit with relation to a rigid sealing diaphragm protector slidable on the plunger and having an annular bulge facing the sealing diaphragm. Another feature is a pump with a reciprocable plunger, a spring for actuating the latter, an oil seal assembly including a flexible sealing diaphragm in part movable with the plunger, and a rigid protector slidable on the plunger and having an annular bulge facing the sealing diaphragm.

These and other important features of the invention will now be described in detail in the specification and then pointed out more particularly in the appended claims.

In the drawings:

FIGURE 1 is an elevational view, drawn partly in section, showing one embodiment of the present invention; and

FIGURE 2 is an enlarged perspective view of parts of the sealing assembly shown in FIGURE 1.

In FIGURE 1, a pump body is depicted as defining a right angle passage 12, a portion of which is shown as a spring chamber 14 and another portion 16 which may be designated as a means of communication with the crankcase of an automobile engine as is customary in automobile fuel pump usage.

A portion of an internal combustion engine in the form of a power rotated cam 18 is shown as engaging the surface 19 of one end of a pump operating lever 20 which is mounted on a shaft 22 held in the pump body 10. A vent 24 is provided leading from the spring chamber 14 and this vent is located closely above a pumping diaphragm illustrate-d at 26. The latter is held tightly between two parts of the body 10 and the lower part of the body contains the usual valves and passages necessary for a diaphragm pump and as illustrated in the Patent No. 3,135,218 above referred to and merely by "ice way of example. The plunger 30 is fixed to the central portion of the pumpingdiaphragm 26 and extends up into the passage 12 and by a shoulder 32 formed as the upper limit of the spring chamber 14. Stop means 34 including three washers 36 and a plunger head 38 are located at the top end of the plunger 30.

A flexible sealing diaphragm 40 in the form of a dished disc of rubber has its hub portion 42 firmly bonded to the plunger 30 and it is also provided with an annular bulge 44 extending toward the pumping diaphragm 26. A rigid sealing diaphragm protector 46 is slidably mounted on and is in contact with the plunger at one side of the protector periphery and its hub is urged toward an abutting relation with the stop means 34. An annular bulge as at 50 is formed on the protector 46 at the other side of the periphery of the latter and this bulge extends in the same direction as the bulge 44 on the sealing diaphragm. An annular centering or spring biased plate 51 surrounds the flexible diaphragm 4t} and is so placed as to center a pumping spring 52 about the plunger 30. The spring 52 is in compression between a protector plate 27 of the diaphragm 26 and the sealing means to hold the latter against the shoulder 32 of the body 10. A coil spring 54, which is smaller than the spring 52, is utilized to promote quiet operation of the pump and as fully described in the aforementioned patent. This spring forms no part of the present invention. Clearance is provided between annular surfaces of the stop means 34 and the sealing diaphragm protector 46 so that a forked end 60 of the actuating lever 20 is insertable to operate the plunger 39 and pumping diaphragm 26.

Conveniently, but not necessarily, the plunger 30 is copper-plated as at 61 and this, in effect, aids in bonding the plunger 30 and diaphragm 40 together so that no relative motion or slippage will occur during pump operation. It will also be appreciated that in practicing the present invention, the pumping instrument-ality or element need not be a pumping diaphragm as shown but could be an enlarged rod or piston.

In view of the one direction bulges 44 and 50, an effective seal is provided against the admission of gasoline vapor to the engine and against the discharge of oil from the engine to the spring chamber 14 and its vent 24. The flexible diaphragm 40 is good for a long life of service as the bulge 50 of the protector 46 prevents reversals of curvature of the sealing diaphragm 40.

It will be appreciated that the sealing diaphragm 40 may have no bulge in it at the bottom of its stroke or in its free state. At the top of its stroke it will have a maximum bulge and at an intermediate stroke position any tendency of the diaphragm 49 to reverse the direction of its bulge is firmly prevented by the rigid protector.

I claim:

1. An oil seal assembly for a reciprocating pump comprising a pumping element and a plunger fixed to said element, a flexible sealing diaphragm mounted on said plunger, a rigid sealing diaphragm protector slidable on and contacting said plunger at one side of the plane of the periphery of said protector and having an annular bulge at the other side of said plane and facing said sealing diaphragm, stop means on said plunger abutting said protector, and spring means interposed between said element and said diaphragm urging said sealing diaphragm and protector toward said stop means.

2. An oil seal assembly for a reciprocating pump comprising a plunger, a pumping element, a flexible sealing diaphragm, a rigid sealing diaphragm protector and spring means all coaxially arranged, annular bulges on said diaphragm and rigid protector extending from the peaasases ripheries of said diaphragm and protector toward said pumping element, one end of said plunger having stop means and the other end fixed to said pumping element, and said spring means being interposed between said pumping element and sealing diaphragm and urging said sealing diaphragm and protector toward said stop means.

3. An oil seal assembly as set forth in claim 2 including an annular centering plate interposed between said spring means and said sealing diaphragm, and said spring means being a coil spring.

4. A reciprocating pump including a pump body enclosing a pumping element, a plunger having one end fixed to said element for actuating the same, a flexible sealing diaphragm with a hub fixed to. said plunger for movement therewith, a rigid protector slidable on said plunger, spring means interposed between said pumping elementand said sealing diaphragm and urging the latter and said protector away from said pumping element, and said protector having an annular bulge surrounding said plunger and extending toward said sealing diaphragm and pumping element.

5. A reciprocable pump including a pump body defining a passage and having an interior shoulder surrounding said passage, a pumping element cooperating with said body to define a spring chamber between said pumping element and said shoulder, a plunger extending into said passage and fixed to said pumping element, a flexible sealing diaphragm having a hub fixed to said plunger for movement therewith, a rigid protector slidable on said plunger, spring means interposed between said pumping element and the peripheries of said sealing diaphragm and rigid protector and retaining the latter in sealing relation with said shoulder, and an annular bulge on said rigid protector arranged to prevent'reversal of curvaure of the flexible sealing diaphragm upon reciprocation of said plunger and pumping element.

6. A reciprocable pump including a pump body having a passage and a shoulder surrounding said passage, a pumping element spaced from said shoulder and determining a spring chamber in said passage, 21 plunger fixed to said element for actuating the same and extending through said spring chamber, a flexible sealing diaphragm with a central portion fixed to said plunger for movement therewith, a rigid protector slidable on said plunger and engaging said shoulder, spring means in said spring chamber and urging said sealing diaphragm and protector against said shoulder, and an annular bulge on said protector and surrounding said plunger to prevent reversal of curvature of the flexible sealing diaphragmf bulge upon recipr'ocation;of said plunger and pumping element.

7. A reciprocable pump as set forth in claim 6 inuding an annular centering plate loosely surrounding said plunger and interposed between said spring means and said sealing diaphragm, and said spring means be? ing a coil spring.

References Cited by theExaminer UNITED STATES PATENTS 2,567,055' 9/1941 Coffey 103 150 MARK NEWMAN, Primary Examiner.

WARREN E. COLEMAN, Examiner. 

5. A RECIPROCABLE PUMP INCLUDING A PUMP BODY DEFINING A PASSAGE AND HAVING A INTERIOR SHOULDER SURROUNDING SAID PASSAGE, A PUMPING ELEMENT COOPERATING WITH SAID BODY TO DEFINE A SPRING CHAMBER BETWEEN SAID PUMPING ELEMENT AND SAID SHOULDER, A PLUNGER EXTENDING INTO SAID PASSAGE AND FIXED TO SAID PUMPING ELEMENT, A FLEXIBLE SEALING DIAPHRAGM HAVING A HUB FIXED TO SAID PLUNGER FOR MOVEMENT THEREWITH, A RIGID PROTECTOR SLIDABLE ON SAID PLUNGER, SPRING MEANS INTERPOSED BETWEEN SAID PUMPING ELEMENT AND THE PERIPHERIES OF SAID SEALING DIAPHRAGM AND RIGID PROTECTOR AND RETAINING THE LATTER IN SEALING RELATION WITH SAID SHOULDER, AND AN ANNULAR BULGE ON SAID RIGID PROTECTOR ARRANGED TO PREVENT REVERSAL OF CURVATURE OF THE FLEXIBLE SEALING DIAPHRAGM UPON RECIPROCATION OF SAID PLUNGER AND PUMPING ELEMENT. 